Document ZJRaLwrK1X3wGbdq0NRmO7yNO

FILE NAME: Ford (FD) DATE: 1971 & 1973 DOC#: FD121 DOCUMENT DESCRIPTION: Internal Memo RE Preliminary Estimate of Airborne Asbestos Emissions from Brake Linings with Cover Letter to R.L. Gealer tntOT Office TO: R. L. G ealer Scientific R esearch Staff June 22, 1973 S u b j e c t : R ep ort SR 7 3 -6 4 I th in k a copy should be se n t a ls o t o Dr. V. Sussman Serge Gratch ed / 009777 8000 Olir produced by ford 9LV) Inter Office Communication Scientific R esea rch Staff O c to b e r 20, 1971 To: cc: Subject: M r. J. U. Damian E. Eichen S. G ratch M. Humenik, J r . D. A. Jensen E . D. M arande J. E. M ayer, Jr. J. V. Petrocelli P relim in a ry E stim a te of A irborne A sb esto s E m issio n s fro m B rake L inings 009778 Some e x p e rim e n ts have been p erfo rm ed w ith the objective of a s s e ss in g the q u an tity of a s b e s to s fib e r em itte d to the a tm o sp h e re du rin g autom obile b ra k in g . A p ro d u c tio n P into d is c b ra k e a s s e m b ly w as used in the stu d y . Sam ples of the niug w ear dust w ere obtained during the lining burnish (break-in), during typical .sage c o n d itio n s (40 m p h s to p s a t 1 /4 G d e c e le r a tio n and 3 5 0 F r o t o r te m p e r a t u r e ) , and d u rin g ab n o rm ally s e v e re usage conditions (~ 800 F r o to r te m p e r a tu re ). Only sam p les from the typical usage test have been exam ined to date. During these te sts, the a ir flow over the b ra k e, w heel and tire a sse m b ly w as carefully m atched to vehicle use conditions. F o r the typical usage te st, all of the a ir flow fro m the brake was exhausted through a sam pling grid network w here m ultiple-stop sam ples w ere taken isokinctically at each grid center using a 0.45 m icron M illipore filter. A m a tc h in g filte r w as used to sam ple the a ir supplied to the b ra k e . The quantity of a s b e s to ^ fib er collected on the filte rs is in the p ro c e ss of being determ ined by e le c tro n m ic ro sc o p e exam ination, using a fib er counting technique developed in the lab o r a t o r y of D r . I. J . S elikoff, et al. . at th e M t. Sinai School of M edicine lr. New Y ork. T h is p r o c e d u r e w a s d ev elo p ed sp e c ific a lly fo r the d e te rm in a tio n of a s b e sto s content from atm ospheric sam ples. The filter exam ination experim ents are not yet com pleted. F u rth er r e p lic a tio n of the fib e r count re m a in s to be done on the ty p ical u sag e f ilte r s to ob tain the p re cisio n c: m e a su re m e n t d e sire d . A ppropriate quantitative referen ce s a m p l e s h a v e n o t y e t b e e n p r e p a r e d a n d c o u n t e d - - t h u s . Ol . . . a., e s tim a te o actual asb e sto s fib e r count re q u ired a reliance on M t. Sn.ai l^c:.ratory experience to e stim a te asb esto s lo sse s fro m the sam ples during sam ple p rep aratio n . N evertne- le s s , a p re lim in a ry estim a te m ay be m ade of the am ount of asb esto s fib er collected b a se d on fib e r co u n ts m a d e to d a te . E x a m in a tio n of th e s e m e a s u r e m e n ts in d ic a te s .hat a s b e s to s f i b e r p ro b a b ly c o m p r is e s l e s s than O.Q2% of the a irb o rn e w e a r d u s t and "may be as low as 0.0047? fo r typical b ra k e u sag e. E x p re ssed in te rm s of the amount of b r a k e lin in g w o rn aw ay , it a p p e a r s th at le s s than 0.017?, and p e rh a p s as little as 8 0 0 0 0 1 1 9 PRODUCED BY FORD q .Mr. J. U. Damian - Z- Octuoer 20, 1971 0.002% of the w orn lining becom es airborne asbestos fib e rs. T he ra n g e of e s tim a te s re s u lts fro m the in h e re n t difficulty of a c cu ra te ly m e a s u r in g s m a ll q u an titie s of such fine fib e rs (300 A d ia m e te r) and fro m the r e la tive sim ilarity of asbestos count from the background-and test filter sam ples. F or exam ple, the te st filte r fro m the typical usage te st collected approxim ately 14.5 x 10 -9 g r am s of a s b e s t o s f i b e r p e r c u b i c m e t e r of a .i r s a m o l e d d o w n w in d of th e b r a k e , -9 w h i l e t h e c o r r e s p o n d i n g b a c k g r o u n d f i l t e r c o l l e c t e d a b o u t 1 3 . 5 x 10 g r a m s p e r cubic m e te r of a ir supplied to the b rak e. Our re c o rd s reveal that asbestos insula-, tio n had been used on a ste a m pipe in the d y n am o m eter a re a about a week p rio r to o u r te s ts and that, other asb esto s insulation w as in stalled elsew here in the building at th e sam e tim e . T his m ay account fo r the re la tiv e ly high background level of a s b e s to s , w hich is at the upper end of the range m e a s u re d by the M t. Sinai laboratory -9 . i n t h e a m b i e n t a i r of th e D e t r o i t a r e a (0 .5 to 1 3 .4 x 10 g r a m s p e r c u b ic m e t e r ) . T he re p o rt of th e ir findings has not yet been published. In conclusion, although only p re lim in a ry re su lts a re available at this 7 tim e , the co n cen tratio n of asb esto s in the effluent a ir fro m a Pinto disc brake undergoing ty p ical b rak e usage ap p ears to be le ss than 0.01% of the brake lining w o rn aw ay. T h e lining w as found to con tain about 42% a s b e s to s , hence the a i r b o rn e a s b e s to s co lle c te d w as le ss than 0.03% of the o rig in al asb e sto s center... O ur lab o rato ry studies have shown that all visible asbestos fibers at an active rubbing interface a re heated to incandescence at typical braking velocities. T he glow te m p e ra tu re (approxim ately 1450F) is m o re than sufficient to decom pose the a s b e s to s to a nonfibrous fo rm . T his probably explains the ex trem ely low am ount of fib ro u s asb e sto s em itted fro m the b ra k e. T he am ount of fib ro u s a s b e s to s re m a in in g w ithin the confines of the b ra k e and w heel assem bly w as not determ ined in this experim ent. Roy L. G ealer C hem ical E ngineering D epartm ent R L G : m s ' A . E A riser so:: M echanical R esearch D epartm ent 009779 PRODUCED BY FORD fto o o n 12 c